The purpose of this study is to rigorously test the efficacy of a couples-based HIV and sexually transmitted infection (HIV/STI) preventive intervention for African American/Black men who have sex with men (MSM) in same sex intimate relationships in which at least one partner is using stimulants (herein referred to as "stimulant-using, African American MSM couples"). The proposed study is a logical progression from the investigative team's prior formative research to take an existing couples based intervention originally for heterosexual couples ("Connect") and revise/tailor it for methamphetamine-using, African American MSM couples. The adapted intervention was pilot tested using a pre-/post-test design. Findings revealed statistically and clinically significant reductions in sexual and drug risk behaviors. In addition, this formative research informs the proposed study in several additional ways: (1) the importance of addressing stimulants beyond methamphetamine with African American MSM;(2) qualitative data on how a couples-based intervention can interrupt relationship dynamics more unique to drug-involved, African American MSM couples that lead to risk behavior;and (3) couples-based HIV prevention research is feasible, promising, and safe for stimulant using, African American MSM. This earlier research has culminated with a 7-session, manualized intervention entitled "Connect 'n Unite" (or CNU-pronounced "seein'you"-for short) as a candidate couples-based HIV preventive intervention for stimulant-using, African American MSM couples. The proposed study is a randomized clinical trial with 270 stimulant-using, African American MSM couples to test the impact of CNU versus a wellness promotion (WP) attention control condition on behavioral and biologically assayed outcomes over a 12-month follow-up period. The study has the following primary aims: (1) to test whether participants assigned to CNU engage in lower HIV/STI behavioral risk-fewer number of unprotected acts of anal intercourse, greater proportion of protected acts of anal intercourse, and fewer number of sexual partners-compared to participants assigned to WP;(2) to test whether participants assigned to CNU have lower cumulative incidence of STIs-chlamydia and gonorrhea-confirmed via biological assay compared to participants assigned to WP;and (3) to test whether participants assigned to CNU engage in less drug use and drug-related HIV risk (i.e., sex under the influence of drugs/alcohol) compared to participants assigned to WP. If successful, this study will advance the field by providing an evidence-based, innovative intervention that can be delivered in drug treatment and other service settings to reduce the spread of HIV among stimulant-using, African American MSM. PUBLIC HEALTH RELEVANCE: This study addresses the overrepresentation of the African American/Black community among those living with HIV/AIDS in the U.S. as well as men who have sex with men (MSM), the transmission category that accounts for the majority of HIV infections. In the absence of a vaccine or cure for HIV infection, behavioral risk reduction represents the best public health tool for prevention of HIV transmission. The proposed randomized clinical trial will rigorously test an innovative, couples-based intervention targeting the intersection of stimulant use and sexual risk behavior among racial/ethnic and sexual minorities, with the ultimate goal providing an evidence-based intervention that can be delivered in drug treatment and other service settings to reduce the spread of HIV among stimulant-using, African American/Black MSM.